Fluid sometimes needs to be drained from a body. For example, urine formed in one or both kidneys might need to be drained into the bladder. One way to accomplish such drainage is to use a medical device that conveys the fluid (e.g., urine) through a lumen. Such devices include stents and catheters. Existing stents can be uncomfortable for the patient, especially when they reside in the ureter between the kidney and the bladder. Moreover, known stents can lead to retention of bodily fluids. For example, oftentimes a stricture develops in the ureter due to irritation of the ureter by the placed stent, thereby blocking urine flow from the kidney into the bladder and leading to retention of urine in the kidney.